Emulsifier-free cationic latexes based on vinylbenzyl chloride and 2-(dimethylamino)ethyl methacrylate with adjusted hydrophilic-hydrophobic properties

Abstract

Functional emulsifier-free cationic latexes based on styrenic monomer vinylbenzyl chloride (VBC) and acrylic monomer 2-(dimethylamino)ethyl methacrylate (DMA) were successfully prepared with dual quaternary ammonium ions (36-63 mol %) on both monomer moieties in two-stages. First, [2-(methacryloyloxy)ethyl]dimethylhexadecylammonium bromide monomer (DMA(C-16)), prepared via quaternization of DMA with 1-bromohexadecane, was utilized as a comonomer (5-20%) as well as a surfactant in the emulsion polymerization of VBC. Next, the quaternization of chloromethyl groups in the VBC moiety in latex particles with trimethylamine and N,N-dimethylhexadecylamine created a second type of quaternized sites on the latex particles. The percentages of the quaternary ammonium ions of the first-stage latexes (P[VBC-DMA(C-16-x)]) and the second-stage latexes (P[VBC(R)-DMA(C-16-x)]) were determined using bromide and chloride ion-selective electrodes. The particles were characterized with a scanning electron microscope, Zetasizer, measuring water contact angles of their pellets. The polymer structure and the alkyl group length in their quaternary ammonium ions played an important role on the sizes, zeta potentials and hydrophilic-hydrophobic balances of the latexes. The water contact angles of the pellets of the latex particles varied from 50.3 to 109.6 degrees depending on both the polymer structure and the alkyl group length